The integrated circuit industry is constantly reducing the separation between conductive layers of material in order to achieve a smaller integrated circuit. By reducing the spacing of conductive materials in an integrated circuit, an increase in a phenomenon known as capacitive crosstalk is observed. Conventional integrated circuits typically use an interconnect structure wherein a first metal line is adjacent a second metal line. If the crosstalk or capacitance between the first metal line and the second metal line is high, then the voltage on the first metal line alters or affects the voltage on the second metal line. This alteration in voltage could cause an integrated circuit to misinterpret logic zeros, logic ones, and voltage levels, and therefore incorrectly process binary and/or analog information. An integrated circuit that incorrectly processes any information is usually totally inoperable.
In order to reduce capacitive coupling and therefore reduce crosstalk, the integrated circuit industry has been developing low dielectric constant (low-K) materials to replace conventional dielectric/insulative materials. Conventional semiconductor insulative materials have a dielectric constant having a value of roughly four. Some new/advanced dielectric materials such as Teflon, organic dielectrics, and the like, may have a dielectric constant between roughly four and two. The use of many low-K dielectric materials is not feasible due to the fact that equipment is not available to properly process the new dielectric materials in various integrated circuits. Also, the chemical or physical properties of many low-K dielectric materials are usually difficult to make compatible or integrate into conventional integrated circuit processing.
Coaxial cable structures and similar structures have been attempted in integrated circuits with little success. A coaxial structure has a first conductor which carries a signal (i.e. a digital signal or an analog signal) and a second conductor surrounding the first conductor which is used to shield the first conductor from other conductors in the integrated circuit. In an integrated circuit, it is very difficult to form a first conductor entirely surrounded by a second conductor. Furthermore, two or more conductive layers are required to form the coaxial structure. Several layers of conductive material are therefore required in order to produce one functional layer of conductive interconnect. Using several conductive layers to form one functional conductive interconnect layer is not substrate surface area effective, manufacturing-throughput effective, or cost effective in most cases.
In order to attempt to reduce capacitive coupling and resistor/capacitor (RC) delays, superconductive material has been researched in the integrated circuit industry. Superconductors require low temperatures in order to operate properly and are therefore expensive to operate and expensive to maintain. In many cases, superconductive material is highly sensitive to oxygen and must be specially encapsulated in integrated circuits to avoid other oxygen containing areas, such as oxides and the like, from introducing unwanted contamination. Superconductors tend to be brittle, and are therefore not suited to integrated manufacturing. In many cases, a superconductor could not survive the mechanical stresses induced on a semiconductor wafer when manufacturing integrated circuits.
A new method and structure for reducing capacitive crosstalk between conductive regions in a semiconductor device is required.